Re: RFA [threads]: Thread cache

[Michael Snyder <msnyder@redhat.com>]

Daniel Jacobowitz wrote:
> 
> On Mon, Jan 13, 2003 at 04:04:20PM -0800, Michael Snyder wrote:
> > Daniel Jacobowitz wrote:

> > > For instance, I'd like to know if I
> > > can safely cache the thread handles across resumes; if I could, this
> > > would be much much much much easier to do efficiently.  We could get
> > > the thread handle and LWP when the thread is created, and then hold the
> > > thread handle, and optionally hold the LWP.  I am pretty sure this is
> > > safe given glibc, but I don't know in general.
> >
> > I think in general not.
> 
> Hmm.  The Solaris documentation suggests that this is valid; I have no
> way to check whether it actually is, and there is no explicit
> description of the lifetime of a thread handle, but it doesn't describe
> them as being of limited life.  It's a handle to "the thread object"
> itself.

Dan, 

I passed your question along to Ulrich Drepper, and he says that, 
if by "thread handle" you mean the th_unique value, then yes, 
those are persistant until the thread exits.  If you mean the
td_thrhandle_t value, though, then no, they are not persistant.
They are allocated by libthread-db as needed, then thrown away.